Although a ba'al mum (a kohen/priest with a blemish or defect) can't approach to bring near to offer food for his G-d (Vayikra/Leviticus 21:17), can't approach to bring near the offerings made by Fire for HaShem (21:21). Which tasks in his role as kohen may he fulfill?

1 Answer
1

The gemara in Yoma 23b (ArtScroll 23b2 notes 12 and 17) in discussing the removal of the ashes, states that the restrictions on a baal mum applies only to those duties which are considered avodah. The gemara states that if removing the ash is considered an avodah (tana kamah), then a kohen baal mum may not do so. Rabbi Eliezer says that it is not an avodah and a kohen baal mum may do so. This would also apply to duties such as guarding the doors, and checking the wood for worms.

Such a kohen must also avoid tum'ah and follow the marriage laws as well as being allowed to eat from the korbanos with the rest of the kohanim. Emor 21:22

His God's food from the most holy and from the holy ones, he may eat.

Rashi

from the most holy: [This phrase] refers to [those sacrifices] with a higher degree of holiness;

and from the holy ones, he may eat: These are the sacrifices with a lesser degree of holiness. Now, if sacrifices with a higher degree
of holiness are mentioned [that a kohen with a defect may eat of
them], why is it necessary to state [the same of] sacrifices with a
lesser degree of holiness? [The answer is that] had they not been
stated, I would have concluded [the following]: Indeed [a kohen] with
a defect may eat of the sacrifices with a higher degree of holiness,
since we find that these were allowed to [be eaten even by] a non-
kohen , since Moses [who was not a kohen ,] ate of the flesh of the
sacrifices of the investitures. Consequently, perhaps the most holy
sacrifices carry with them this leniency]. The breast and thigh of
sacrifices with a lesser degree of holiness, however, shall not be
eaten [by a kohen with a defect], for we do not find an instance where
a non- kohen takes a share of these!“ Therefore, Scripture states here
”or from the holy" [thereby permitting a kohen with a defect to eat
from the sacrifices with a lesser degree of holiness as well]. In this
way the matter is explained in [Tractate] Zevachim (101b).